PHOTOREGULATORY SIGNAL TRANSDUCTION

对蓝光做出反应的能力广泛存在于 生物王国。这些回复中的许多，包括在 细菌、真菌、昆虫和植物被认为是由 黄素蛋白。尽管蓝光反应是第一个 达尔文在100多年前描述过，到目前为止还没有这样的光感受器 都被描述过。 这一建议是基于最近对 拟南芥的HY4基因。有缺陷的突变植物 这个基因表现出对蓝光的选择性不敏感。按顺序排列 HY4基因与微生物光解酶基因有惊人的相似性。 这些酶是一类罕见的黄素蛋白，可以修复紫外线损伤的DNA。 并被蓝光或紫外光的吸收激活；即； 它们的功能是光感受器。这种表型的组合 Hy4突变株的特性及其与光解酶的序列相似性 令人信服的证据表明HY4编码了一种基于黄素的蓝光 光感受器。 这一提议是生化、分子和遗传学的结合。 进一步研究HY4感光细胞特性的途径。 涉及电生理学和生物物理学的协作研究 方法也包括在内。将从转基因烟草中提纯HY4 植物以及拟南芥，并将尝试过度表达 在酵母和杆状病毒感染的异源表达系统中 昆虫细胞。纯化的蛋白质将用于旨在 确定其生化特征，包括其性质 生色团。根据光解酶的性质，人们认为 HY4将作为氧化还原剂发挥作用。HY4对蓝色的调节能力 离体血浆氧化还原性质的光依赖性变化 将对膜进行检查，分子和遗传方法都将 用于搜索光调节信号中的附加成分 转导途径。 感知和响应光的能力在整个人类社会中都是普遍存在的 生物王国和信号机制的性质，这些机制是 与这些反应相关的问题引起了广泛的兴趣。同样重要的是， 尤其是在研究人类中性粒细胞和吞噬功能时， 氧化还原反应影响细胞活性的途径 膜。建议的研究，充分利用 对拟南芥的分子和遗传分析，将提供一个 对我们理解这些重要的 流程。

The ability to respond to blue light is widespread throughout the biological kingdom. Many of these responses, including some found in bacteria, fungi, insects and plants, are believed to be mediated by flavoproteins. In spite of the fact that blue light responses were first described by Darwin over 100 years ago, no such photoreceptor has hitherto been described. This proposal is based on the recent isolation and characterization of the HY4 gene of Arabidopsis thaiiana. Mutant plants that are defective for this gene show a selective insensitivity to blue light. The sequence of the HY4 gene shows a striking similarity to that of microbial photolyases. These enzymes are a rare class of flavoproteins that repair UV-damaged DNA and are activated by the absorption of either blue or UV light; that is; they function as photoreceptors. This combination of the phenotypic characteristics of hy4 mutants and the sequence similarity to photolyases is compelling evidence that HY4 encodes a flavin-based blue light photoreceptor. This proposal is a combination of biochemical, molecular, and genetic approaches to the further characterization of the HY4 photoreceptor. Collaborative studies involving electrophysiological and biophysical approaches are also included. HY4 will be purified from transgenic tobacco plants, as well as Arabidopsis, and attempts will be made to overexpress it in heterologous expression systems in yeast and baculovirus infected insect cells. The purified protein will be used in studies aimed at determining its biochemical characteristics including the nature of the chromophores. Based on the properties of photolyases, it is believed that HY4 will function as a redox agent. The ability of HY4 to mediate blue light-dependent changes in the redox properties of isolated plasma membranes will be examined and both molecular and genetic approaches will be used to search for additional components in the photoregulatory signal transduction pathway. The ability to perceive and respond to light is universal throughout the biological kingdom and the nature of the signaling mechanisms that are associated with these responses is of wide interest. Equally important, especially in the study of human neutrophils and phagocytosis, is the means by which redox reactions impact on the activity of cellular membranes. The proposed studies, taking full advantage of the merits of both molecular and genetic analysis in Arabidopsis, will provide a significant contribution to our understanding of these important processes.